# Memo: Internal — Pipeline Safety Interpretation **Citation:** PI-83-009 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 1983-06-27 PI-83-009 response to Memo: Internal concerning 192.321. ## Document text <<>> June 27, 1983 INFORMATION: Interpretation - §192.321(b) Richard L. Beam Associate Director for Pipeline Safety Regulation, DMT-30 Richard E. Sanders Program Manager Pipeline Safety Program, TSI, DMA-60 In response to your memo of May 3, 1983, requesting an inter- pretation of §192.321(b) relative to the intent of the phrase "a vault or any other below grade enclosure," OPSR has reviewed the problem. Attached is a pipeline safety regulatory interpretation relative to your question. # Attachment dal\192\321\83-06-27 1 <<>> No. 83-7 Date: June 27, 1983 DEPARTMENT OF TRANSPORTATION RESEARCH AND SPECIAL PROGRAMS ADMINISTRATION MATERIALS TRANSPORTATION BUREAU _ PIPELINE SAFETY REGULATORY INTERPRETATION Note: This pipeline safety regulatory interpretation applies to all operators that are subject to the rule under Federal or State law. SECTION: 192.321(b) SUBJECT: Installation of plastic pipe. FACTS: 1. 2. 3. §192.321(b) reads, "Plastic pipe that is installed in a vault or any other below grade enclosure must be completely encased in gas-tight metal pipe and fittings that are adequately protected from corrosion." Some operators are installing plastic valve boxes at the property line and bringing a small loop of the plastic service line into the plastic valve box. Also, some operators are placing concrete meter boxes, plastic valve boxes, and other similar configurations on existing lateral lines. Both of these are installed so that in an emergency the operator can quickly stop the gas flow by squeezing off the plastic pipe. Some operators are inserting polyethylene plastic pipe into PVC for road crossings. QUESTION: Would §192.321(b) prohibit these installations? INTERPRETATION: None of the cases discussed above are included in the intended meaning of "a vault or any other below grade enclosure" as used in §192.321(b). The intent of this section is to require protection against mechanical or heat damage of plastic pipe and, in the event of a failure, protect the occupants of a vault or other below grade enclosure from the effects of escaping gas. If 2 dal\192\321\83-06-27 2 <<>> the plastic pipe in the installations described above is not subject to anticipated mechanical damage or heat damage and the space is not subject to human occupancy, then the casing would serve no useful purpose. However, with regard to the road crossing insertions, if plastic pipe is used as a casing "on a transmission line or main under a railroad or highway," it must meet the requirements of §192.323, also. Richard L. Beam Associate Director for Pipeline Safety Regulation Materials Transportation Bureau dal\192\321\83-06-27 3 <<>> DATE: May 3, 1983 SUBJECT: ACTION: Request Code Interpretation - Subpart 192.321(b) FROM: Richard E. Sanders Program Manager, Pipeline Safety Program TO:Richard L. Beams Associate Director, Office of Pipeline Safety Regulations, DMT-30 I find in Rule 192.321, "Installation of Plastic Pipe", (b) that plastic pipe that is installed in a vault or any other below-ground enclosure must be completely encased in a gas-tight metal pipe and fittings that are adequately protected from corrosion. I have noted several situations in talking with operators throughout the country concerning this section. Some operators are installing plastic valve boxes at the property line and bringing a small loop of 1/2" CTS plastic into the plastic valve box. Also some operators are placing concrete meter boxes, plastic valve boxes, and other similar configurations on existing lateral lines so that in an emergency the operator can go to these below-ground enclosures and squeeze off the plastic pipe without having to put in valves. Since 192.321 is in the construction subpart of the code, I am wondering whether or not new construction using these practices would meet the intent of 192.321. Also, I am concerned about systems where this practice is being used a retrofit which would fall under the maintenance section of the code and in turn, I cannot find anything under the maintenance section that would give guidance on whether or not this would be acceptable. Another area of concern is that some operators are inserting polyethylene plastic pipe into PVC (poly vinyl chloride plastic) for road crossings. Would the requirements of 192.321 disallow this practice because of the requirements indicated in (b) of 192.321? Your assistance and comments on these areas would be appreciated. # Research and Special Programs Administration dal\192\321\83-06-27 4 <<>> 49 CFR Part 192 [Interpretation 83-7] Transportation of Natural and Other Gas by Pipeline; Installation of Plastic Pipe AGENCY: Materials Transportation Bureau (MTB), Research and Special Programs Administration, DOT. ACTION: Interpretation. SUMMARY: The Research and Special Programs Administration (RSPA) is issuing this interpretation of the phrase "vault or any other below grade enclosure" as it appears that phrase appears in paragraph (b) of §192.321, installation of plastic pipe. The interpretation was requested by the Office of Enforcement field compliance staff. This interpretation clarifies the intent of the phrase. EFFECTIVE DATE: August 22, 1983. FOR FURTHER INFORMATION CONTACT: Paul J. Cory, (202)426-2082. SUPPLEMENTARY INFORMATION: Interpretation 83-7. Section: §192.321(b). Subject: Installation of plastic pipe. Facts 1. Section 192.321(b) reads, "Plastic pipe that is installed in a vault or any other below grade enclosure must be completely encased in gas-tight metal pipe and fittings that are adequately protected from corrosion." 2. Some operators are installing plastic valve boxes at the property line and bringing a small loop of the plastic service line into the plastic valve box. Also, some operators are placing concrete meter boxes, plastic valve boxes, and other similar configurations on existing lateral lines. Both of these are installed so that in an emergency the operator can quickly stop the gas flow by squeezing off the plastic pipe. 3. Some operators are inserting polyethylene plastic pipe into PVC for road crossings. Question: Would §192.321(b) prohibit these installations? Interpretation: None of the cases discussed above are included in the intended meaning of "a vault or any other below grade enclosure" as used in §192.321(b). The intent of this section is to require protection against dal\192\321\83-06-27 mechanical or heat damage of plastic pipe and, in the event of a failure, protect the occupants of a vault or other below grade enclosure from the effects of escaping gas. If the plastic pipe in the installations described above is not subject to anticipated mechanical damage or heat damage and the space is not subject to human occupancy, then the casing would serve no useful purpose. However, with regard to the road crossing insertions, if plastic pipe is used as a casing "on a transmission line or mail under a railroad or highway," it must meet the requirements of §192.323, also. Lists of Subjects in 49 CFR Part 192 Pipeline safety. (49 U.S.C. 1672 and 1804; 49 CFR 1.53, Appendix A to Part 1, and Appendix A to Part 106) Issued in Washington, D.C. on June 27, 1983. Richard L. Beam, Associate Director for Pipeline Safety Regulation, Materials Transportation Bureau. 5 ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `78104d194104b06e96b1e303dd2f032395bbe3a63f6ab9447f0f6411a2bfb71c` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-23T09:20:45.336Z - Document slug: `phmsa-interpretation-pi-83-009` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "pipeline_safety", "representation": "full_text_from_official_pdf", "companies": [ "Memo: Internal" ], "individuals": [], "refIds": [ "PI-83-009" ], "catalogDates": [ "1983-06-27" ], "catalogParts": [ 192 ], "catalogRowCount": 1, "sourceRecordUrls": [ "https://www.phmsa.dot.gov/node/60371" ], "linkedAttachmentUrls": [], "unavailableResponseUrls": [], "duplicateRepresentationUrls": [], "citedSections": [ "192.321", "192.321(b)", "192.323" ], "catalogPageUrls": [ "https://www.phmsa.dot.gov/regulations/title49/section/192321" ], "pdfUrls": [ "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1983/PI83009.pdf" ], "representations": [ { "viewUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1983/PI83009.pdf", "detailUrl": null, "detailHtmlPath": null, "pdfUrl": "https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/legacy/interpretations/Interpretation%20Files/Pipeline/1983/PI83009.pdf", "pdfArtifactPath": "data/sources/phmsa-interpretations/pi-83-009.pdf", "pdfArtifactSha256": "5875f43c152050525315e457e9479ce29c6a95ffe3d1e9f594cd6e00849f0c92", "extractedTextPath": "data/sources/phmsa-interpretations/pi-83-009.v2.txt", "extractedTextSha256": "98167f07f515f0ea2bf6d2c52fe089d21b3f0e9a8d73d1234a153f7f9e49870a", "pageCount": 5, "extractionVersion": 2 } ], "caveat": "Interpretations apply regulations to the facts presented and do not create independently enforceable requirements.", "jurisdiction": "US" } ```